Lead-in seal



A. J. KLING LEAD-IN SEAL Jan. 6, 1942.

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Inventor August. J. Kling, b9 JV tborneg.

Patented Jan. 6, 1942 LEAD-IN SEAL August J. Kling, Schenectady, N. Y., assignor to General Electric Company, a corporation of New York Application April 26, 1940, Serial No. 331,792

10 Claims.

This invention relates to seals having means to carry current through the walls of vitreous vessels, such for example, as cathode ray tubes, and has for an object to provide an improved type of seal for carrying current through the vitreous walls of a sealed vessel where a compact structure which imposes minimum strain on the wall is necessary. x

It is also an object of my invention to provide an improved seal whose terminals are closely adjacent the Walls of the vessel whereby the vessel may be passed through or remain in spaces not substantially larger than the vessel without the terminals.

It is a further object of my invention to provide special terminals for such a seal, which are capable of withstanding considerable mechanical strain imposed by connections made thereto with minimum danger of breaking th vitreous walls.

The features of my invention which I believe to be novel are set forth with particularity in the appended claims. My invention itself, however, both as to its organization and method of operation, together with further objects and advantages thereof, may best be understoodby reference to the following description taken in connection with the accompanying drawing in which Figs. 1 and 2, respectively, are cross-sectional side and end views of a portion of a cylindrical vitreous vessel embodying my invention, and Figs. 3, 4, and 6, respectively, represent somewhat different modifications of my invention.

Fig. 1 illustrates a portion of a tubular vitreous vessel I0, which may, for example, be made of glass or quartz, having a ribbon II of metal foil passing therethrough at one point. The ends of the foil, which suitably consists of platinum, are bent over to lie continguous with the wall of the vessel. This foil must have a thickness considerably less than one mil and is preferably about fifteen-hundredths to twenty-hundredths of a mil thick. The use of a conductor with such limited transverse dimensions is desirable to avoid any strain on the wall I0 through which the foil II is sealed.

The process by which this foil II is sealed through the wall III comprises first, melting a hole through the wall I0 sufliciently large to allow the foil II to pass therethrough and, second, rescaling the wall III, with or without additional vitreous material, around the foil I I to restore the original uniform shape of the wall. After the ribbon II has been sealed within the wall, the

externally accessible ends thereof are pressed down flush with the wall to occupy a minimum amount of space.

Since the ribbon foil II has slight mechanical strength, a coating I2 of a conducting material, such, for example, as a point containing a metal, is applied over the portion of the foil I I externally accessible and lying contiguous to the wall. This coating I2 is adapted to provide mechanical protection for the foil while at the same time being capable of conducting current thereto.

Conducting coatings, such as described above, are well known and may, for example, comprise a mixture of oil solvent, low melting point glass, and metal powder. After being painted in place, such paints are baked on and the solvent is burned away to leave a vitreous mass, which is nevertheless conducting since it is impregnated with metal. Metals suitable for mixture in such paints are gold, silver, platinum, and the like.

Certain types of such conducting paints have no glass therein and include essential oils and chlorides of the metal desired. During firing, the oils burn away and a very hard, bright coating of the metal remains, which is burned into the vitreous material on which it is fired. Such lat ter coatings are much lighter than those containing glass.

' stricted spaces, as through holes within magnetic coils or the like. At the same time, the seal provides a mechanically rugged and reliable means for carrying current through the wall of a sealed vitreous vessel.

In Fig. 3, a modification of the above-described seal is shown wherein, in addition to the single foil II, which is embedded partially within the wall I0, there is supplied an additional foil I3 of similar form. The hole melted through the wall I0 must be sufiiciently big to accommodate both the ribbons II and I3, spaced apart a small distance. In resealing the hole, vitreous material is added not only around and between the ribbons II and I3, but is also added on the exterior of the wall I0, so that the surface of the wall is caused locally to assume the shape of a knob I4. The knob I4 is not, however, made sufficiently large to cover the projecting end portions I5 and I6 of the ribbons II and I3. A coating I! of conducting material is applied over the knob I4 and Subsequently,

in contact with both of the projecting ends I! and Hi.

This form of seal is especially useful where it the knob are under minimum internal strain and are accordingly strong and rugged. A conducting path extends from such a spring clip to the conducting coating to the projecting end portions l5 and I3, and thence through the ribbons I I and I3 to the interior of the glass tube III.

In Fig. 4, there is illustrated a partially completed seal in which six portions of foil l8, I9, 20, 2|, 22, 23 are provided. As illustrated, the upper heavy lined portions are seen on the surface of the wall and the light lined portions are seen through the vitreous material of the wall. In making such a seal a relatively large hole is melted in the wall It! and the six above-mentioned portions of foil are placed therethrough. additional vitreous material is melted into the hole around and between the foil portions i8-23 to restore the original shape of the wall II). A coating of conducting paint, such as illustrated in Fig. 1, may then be applied over either or both sides of the wall ID to make connection with and protect mechanically the portions of foil unembedded in the wall.

The structure as illustrated in Figs. 3 and 4, of course, provides for greater current-carrying capacity than where a single portion of foil is utilized, as in the structure of Fig. 1. There is,

however, an important additional advantage in that, if one of the .portions of foil is injured during.the process of forming the seal, the other portions of foil maintain a conductive connec tion through the wall. The aforementioned embodiments of my invention have been described as utilized in vessels formed of glass, quartz, or the like. In glass vessels it is highly desirable to use platinum or rhodium foil of the above-specified thickness. In quartz vessels it is desirable to use foil formed of iridium. In any specific case, where the vessel be formed of glass, quartz, or other materials, it is necessary that a conducting foil be used which will neither oxidize nor melt at the melting temperature of the material of the vessel. Such foil materials are herein termed refractory.

Fig. 5 illustrates a structure in which it is desirable to make a seal having substantial mechanical strength for mounting elements on the interior of a vitreous vessel. In this modification a portion 24 of foil is welded or otherwise fastened to a small, relatively heavy piece of metal 25. The foil 24 and piece of metal 25 are sealed through the glass wall I0 so that the foil projects on the exterior and the piece of metal 25 on the interior. A coating of vitreous conducting paint 26 may be spread over the unembedded portion of the foil 24 to form the exterior connection. The piece of metal 25 is embedded in the wall I 0 only enough to form an internal connection with considerable mechanical strength. The

Glass wall ll, aflord the filament chanical support. a

As illustrated, the foil 2'! at the exterior of the glass tube In may make connection with a coating of conducting material on a glass knob III, similar to the knob i4 and coating 11 illustrated in Fig. 3. Of course, if desired, a flush seal may be utilized on both sidesof the tube ID in Fig. 5.

Fig. 6 illustrates a very convenient means of providing a seal for carrying current to a metal disk 32, which is sealed in the glass tube It so as to close the passage therethrough except for a small aperture 33 in the center of the disk 32. In this embodimenta sea l of the form illustrated by Fig. 1 may prove useful if it be desired to provide a structure suitable for use in small space, since the ribbon foil H and the conducting coating J2 do not project substantially on the exterior of the tube Ill. The interior pressed-down projecting end of the foil ii is covered with a 28 ample me- -coating 34 of conducting paint, which also ex- 7 tends for a small distance on the wall I0 and upon disk 32 to make a conductive connection thereto. Current may therefore fiow from the disk 32 through the coating 34 and ribbon foil II, and through the coating i2 to any desired connecting means.

While I have shown particular embodiments of my invention, it will, of course, be understood that I do not wish to be limited thereto, since different modifications may be made both in the instrumentalities employed and in the arrangement thereof, and I aim by the appended claims to cover any such modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In combination with a wall of vitreous material, means for conducting current therethrough comprising a refractory metal foil embedded in said wall, said foil having an externally accessible portion following the contour of said wall and lying contiguous thereto, a vitreous projection formed integrally with said wall and adjacent said externally accessible portion, said projection being shaped to facilitate making a mechanical connection thereto, and a coating of conducting material over said projection and said externally accessible portion providing mechanical protection for said foil, whereby there is a conducting path from said foil through the coating on said projection.

2. In combination with a wall of vitreous maten'aL- means for conducting current therethrough comprising a conductor embedded in said wall having an externally accessible portion following the contour of said wall and lying contiguous thereto, said conductor having a transverse dimension so small as not to impose appreciable strain on the vitreous material by its presence therein, a vitreous projection formed integrally with said wall and partially covering the externally accessible portion of said conductor, said projection being shaped to facilitate making a mechanical connection thereto, a coating of conducting material over said projection and said externally accessible portion providing mechanical protection for said conductor, said current conducting means providing a conducting path through said conductor and through said coating.

3. In combination with a wall of vitreous material, means for conducting current therethrough comprising a-metal foil embedded in said wall, said foil having an externally accessible portion following the contour of said wall and lying contiguous thereto, said foil being of limited thickness so as not to impose appreciable strain on the vitreous material by its presence therein, a vitreous projection formed integrally with said wall and partially covering said externally accessible portion, said projection having an enlarged end portion and a reduced shank portion shaped to facilitate making mechanical connection thereto, and a coating of conducting material over the uncovered part of said foil and over said projection to provide mechanical protection for said foil, said current conducting means providing a conducting path through said foil and said coating.

4. In combination with a wall of vitreous ma-' terial, means for conducting current therethrough comprising a metal foil embedded in said wall, said metal foil having an externally accessible portion following the contour of the wall and lying contiguous thereto, said foil being of limited thickness so as not to impose appreciable strain on the vitreous material by its presence therein, a vitreous projection formed integrally with said wall and partially covering said externally accessible portion, said projection being shaped to facilitate making mechanical connection thereto, a coating of conducting material over said projection and said external-' sible end portion following the contour of the outer surface of said wall and lying contiguous thereto, said foil being of limited thickness so as not to impose appreciable strain on the vitreous material by its presence therein, a vitreous projection formed integrally with said wall and adjacent said externally accessible portion, said projection being shaped to facilitate making me chanical connection thereto, a coating of conducting material over said projection and over said adjacent externally accessible portion to provide mechanical protection therefor, an electrical device supported between said opposed walls and conductively connected to the other end portion of said metal foil, whereby an electrical path exists from said coating through said foil to said electrical device.

6. In combination with a body of vitreous material, means for conducting current therethrough comprising a conductor embedded therein, said conductor having an externally accessible portion following the contour of the adjacent surface of said body and lying contiguous thereto, a vitreous projection integral with said body adjacent said externally accessible portion, said projection being shaped to facilitate making a mechanical connection thereto, and a coating of conducting material over said projection and said externally accessible portion providing mechanical protection for said conductor, whereby a conducting path is formed from said conductor through said coating to the mechanical connection upon said projection.

7. In combination with a body of vitreous ma terial, means for conducting current therethrough comprising a conductor embedded therein, said conductor having an externally accessible portion following the contour of the adjacent surface of said body and lying contiguous thereto, and a vitreous projection integral with said body adjacent said externally accessible portion, said projection being of knob-like form, thereby to facilitate the mechanical attachment of a terminal clip to said body and to hold the terminal clip in a position adjacent said body and said conductor.

8. An electron discharge device comprising an envelope of insulating material, a hole in the wall of the envelope, metallic means contiguous with the side of said hole having portions following contiguously the external contour of the surfaces of said wall adjacent said hole, and a plug sealed gas-tight in said hole.

9. A lead-in connection through a wall of insulating material, comprising a hole through the wall, a conductor through the hole contiguous with a side thereof and following contiguously' the external contour of the wall adjacent the hole, and a mass of sealing material fixed in gastight union with the sides of the hole.

10. A lead-in connection through a wall of insulating material, comprising a hole through the wall, conducting means on the opposite exposed surfaces of the wall and on a side of said hole, a

such means being disposed in continuous conductive relation, and means hermetically sealing said hole.

AUGUST J. KLING. 

